Mast cells play a key role in the inflammatory process. They are found in the perivascular spaces of most tissues and contain pro-inflammatory and vasoactive mediators, such as serine proteases, tryptase, histamine, serotonin, proteoglycans, thromboxane, prostaglandin D2, leukotriene C4, platelet-activating factor, and eosinophil chemotactic factor. When activated, mast cells rapidly release granules and various hormone mediators into the interstitium, a process referred to as degranulation. Degranulation of mast cells can be caused by physical or chemical injury, crosslinking of immunoglobulin G receptors, or by activated complement proteins.
Systemic mast cell related disorders may result from excessive proliferation of mast cells or abnormal release of pro-inflammatory and vasoactive mediators. Symptoms of systemic mast cell related disorders include pruritus, flushing, nausea, vomiting, diarrhea, headaches, abdominal pain, vascular instability, urticaria, itching, and anaphylaxis. Accumulation of mast cells in the skin, gastrointestinal tract, bone marrow, liver, spleen, and lymph nodes may result in a particular systemic mast cell related disorder, systemic mastocytosis, or mastocytosis.
The utility of mast cell stabilizers in the treatment of systemic mast cell related disorders, such as mastocytosis, has been limited. For example, cromolyn sodium (also known as disodium cromoglycate or DSCG) was first approved in 1973 and is widely considered safe, but it has found limited utility because the amount of the compound that can be delivered systemically is inadequate. An oral solution of cromolyn sodium is available for the treatment of systemic mast cell related disorders, such as mastocytosis (Gastrocrom®). However, the oral solution is only modestly effective for treating localized gastrointestinal symptoms, and it is not effective for the treatment of systemic symptoms because of the low oral bioavailability of cromolyn sodium (less than 1%).
Efforts have been made to increase the oral bioavailability of cromolyn sodium in order to provide systemically effective amounts for the treatment of systemic mast cell related disorders, but these efforts have not yielded products that achieve significantly higher oral bioavailability of cromolyn sodium in a practical, safe, and well-tolerated manner. Accordingly, a need exists for methods of delivering mast cell stabilizers, such as cromolyn sodium, that achieve higher systemic levels than previously considered or thought possible, in a practical, safe, and well-tolerated manner, in order to significantly improve clinical outcomes for patients suffering from systemic mast cell related disorders.